Redox Buffering of Hypochlorous Acid by Thiocyanate in Physiologic Fluids

The major antimicrobial products of neutrophilic myeloperoxidase (MPO) in physiologic fluids are hypochlorous acid (HOCl) and hypothiocyanite (OSCN-), and the former is generally believed to be the killing agent. However, we have determined that HOCl oxidizes SCN- in a facile nonenzymic reaction. Th...

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Bibliographic Details
Published in:Journal of the American Chemical Society 2004-12, Vol.126 (49), p.15976-15977
Main Authors: Ashby, Michael T, Carlson, Amy C, Scott, M. Jared
Format: Article
Language:English
Subjects:
Biological and medical sciences
Buffers
Electrochemistry
Fundamental and applied biological sciences. Psychology
Humans
Hydrogen Peroxide - chemistry
Hydrogen Peroxide - metabolism
Hypochlorous Acid - blood
Hypochlorous Acid - chemistry
Hypochlorous Acid - metabolism
Kinetics
Molecular biophysics
Oxidation-Reduction
Peroxidase - metabolism
Physical chemistry in biology
Serum Albumin - chemistry
Serum Albumin - metabolism
Substrate Specificity
Thiocyanates - blood
Thiocyanates - chemistry
Thiocyanates - metabolism
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Summary:The major antimicrobial products of neutrophilic myeloperoxidase (MPO) in physiologic fluids are hypochlorous acid (HOCl) and hypothiocyanite (OSCN-), and the former is generally believed to be the killing agent. However, we have determined that HOCl oxidizes SCN- in a facile nonenzymic reaction. The observed kinetics and computational models substantiate the hypothesis that SCN- serves to moderate the potential autotoxicity of HOCl by restricting its lifetime in physiologic fluids. Furthermore, the oxidizing equivalents of HOCl are preserved in OSCN-, a more discriminate biocide that is not lethal to mammalian cells.
ISSN:0002-7863
1520-5126
DOI:10.1021/ja0438361